The roofs of such buildings generally comprise framing made of metal, concrete, or wood, having roofing elements fixed thereto.
Roofing elements in the form of ribbed metal plates fixed on purlins extending between the rafters of the framing are known. Such metal plates are covered in insulation and asphalt sealing layers. Such roofing elements require framing that is complex, using multiple components that are assembled together on site. Such roofs are thus relatively time-consuming and expensive to build and they also turn out to be dangerous, given the number of operations which need to be performed at height. In addition, the asphalt layers require maintenance operations relatively frequently and they have a lifetime that does not exceed about 15 years. Furthermore, given their composition, the asphalt layers tend to facilitate the propagation of fire.
In order to mitigate that drawback, roofs of that type are generally covered in a layer of gravel chippings that is several centimeters thick, thereby limiting the propagation of flames cowards the top of the roof. However that makes the roof more complicated to build and significantly heavier.
Roofing elements in the form of corrugated metal sheets sandwiching an insulating layer are also used. Such roofing elements can be made to be relatively long so they can be mounted directly between the rafters of the framework without having recourse to purlins. Nevertheless, those roofing elements are generally quite thick, about 2 meters (m) thick for the longest spans. The use of such roofing elements thus leads either to a considerable increase in the outside height of the building, or else to a considerable decrease in the inside height thereof.